"I second what nevadanick says-pocket aces against a rando hand wins 85.5% of the time, against 4 rando hands it wins 55.8% of the time. If you're going to go all in with it you don't want a lot of people in with you. Numbers courtesy of Phil Gordon."
85.5% win 100 = average return of plus 85.5
15.5% lose 100 = average returrn of -15.5
of situation = +70
55.8% chance to win 400 = +223.20
44.2% chance to lose 100 = -44.20
Expected value of situation = +179
So if this is a tournament, I guess you'd have to decide if an expected value if 1.79 times your chips stack is worth a 44% chance of busting out. Most situations, it is.
If this is a cash game, and you don't want more callers, you just hate money.